Poly-L-Lysine@gold nanostructured hybrid platform for Lysozyme aptamer sandwich-based detection

A novel hybrid platform of conductive Poly-L-Lysine (Poly-L-Lys) and gold nanostructures (NSs) was prepared for the development of a sandwich-structured aptasensor towards the sensitive and selective detection of Lysozyme (Lyz). Electrodeposition of Poly-L-Lys-at screen-printed carbon electrodes (SPCE) was done, followed by the gold deposition from a solution containing HAuCl4 and 10,000 Polyethylene glycol (PEG). The concentration of the HAuCl4 solution was the key parameter in controlling the morphology of the platform, confirmed by scanning electron microscopy and atomic force microscopy. Electrochemical characterization of the hybrid platforms demonstrated differences in the electrochemical voltammetric and impedance properties of the platform obtained using 2 mM HAuCl4 (AuNSs(I)@PEG/Poly-L-Lys/SPCE) and 20 mM HAuCl4 (AuNSs(II)@PEG/Poly-L-Lys/SPCE). All steps involved in the aptasensor development were evaluated to determine the optimum sensor configuration for Lyz detection. The aptasensor with the best configuration was applied in a wide linear range (70–7 × 105 pM), and a limit of detection of 2 pM was calculated (3*σ/slope). The applicability of the electrochemical aptasensor was demonstrated by the successful quantification of Lyz in wine samples.